Manifolded multiple hydraulic pump structure

ABSTRACT

An improved hydraulic pump structure for hydraulic systems which require a plurality of rotary pumps has a pump casing assembly (20) consisting of a plurality of pump casing elements (23-29) which are fastened together in abutting relationship to define a first pump cavity (54) and a second pump cavity (55a) with aligned drive shaft holes (56-61) and a drive shaft (62-63) which is journalled in the holes (56-61) and carries a rotary pump member (76-77 or 80-81) in each cavity (54 and 55a). The casing elements (23-29) are manifolded to provide a first fluid inlet passage (82), a first fluid delivery passage (84) which terminates in a port in a fluid delivery end plate (29), a second fluid inlet passage (86) which has an entrance opening (H6) in the fluid delivery end plate (29), and a second fluid outlet passage (87) which terminates in a port in the fluid delivery end plate (29). There may be two subassemblies (21 and 22) with two pumps in each, secured together in face abutting relationship with an axially interengaged driving connection (62a-63a) between drive shaft segments (62 and 63) in the two subassemblies (21 and 22) and with fluid delivery passages (83 and 84) extending from one assembly through the other.

TECHNICAL FIELD

This invention relates to a manifolded, multiple hydraulic pumpstructure which may be used wherever two or more rotary pumps may bedriven by a single drive shaft. It is expressly disclosed herein asapplied to a heavy vehicle having a hydraulic transmission and ahydraulic torque converter; but is not limited to such application.

BACKGROUND ART

There are numerous situations in which a hydraulic power circuitrequires a plurality of rotary pumps to supply fluid to various powerelements in the system. Commonly such pumps are completely independentof one another, which requires plural mountings and a substantial numberof conduits of varying length, all of which are subject to possibleleakage at their various connections and to breakage under operatingstress. The arrangement of separate pumps, separately mounted, givesvery poor space utilization and requires a separate drive train to eachof the pumps.

Typical of such hydraulic systems are those in heavy vehicles, such ascrawler tractors, wheel loaders, and large capacity dump trucks. Suchvehicles commonly have a hydraulic transmission and a hydraulic torqueconverter. The hydraulic system for such a vehicle requires a chargingpump for the hydraulic transmission, a fluid conduit from the pump tothe transmission, a charging pump for the torque converter, a fluidconduit from the torque converter charging pump to the torque converter,scavenging pumps, scavenging conduits from the transmission and thetorque converter to the scavenging pumps, fluid delivery lines to bothcharging pumps, and return lines from the scavenging pumps to the sump.

DISCLOSURE OF INVENTION

The present invention is directed to overcoming one or more of theproblems as set forth above.

According to the present invention, an improved pump structure has apump casing assembly consisting of a plurality of rotary pump casingelements disposed in face abutting relationship, with sealing meansbetween the casing elements and means detachably securing the casingelements in assembled, face abutting relationship. The casing elementscooperate to define a first pump cavity and a second pump cavity, with asingle drive shaft extending through an opening in a drive end plate ofthe casing elements and through both pump cavities in each of which itcarries a rotary pump member. The casing elements also are provided witha plurality of manifold passages including a first fluid inlet passagefor admitting fluid to the first pump, a first fluid delivery passagefrom the first pump which has a port in a fluid delivery end plate ofthe casing elements, a second fluid inlet passage and a second fluidoutlet passage.

When the invention is applied to a heavy vehicle which has a hydraulictransmission and a hydraulic torque converter, the pump casing elementsdefine a transmission charging pump cavity and a torque convertercharging pump cavity with the drive shaft extending through bothcavities and a rotary charging pump member in each cavity, the chargingfluid inlet passage also supplies the torque converter pump cavity,there is a torque converter charging fluid delivery passage from thatpump to a charging fluid port in the fluid delivery end plate, and asecond scavenging pump which also has a pump member on the drive shaft.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side elevational view of the improved hydraulic pumpstructure of the present invention, mounted upon a gear housing wall ofa heavy vehicle, with parts broken away and illustrated in section;

FIG. 2 is an end elevational view illustrating the fluid delivery end ofthe pump structure, taken substantially as indicated along the lineII--II of FIG. 1;

FIG. 3 is an elevational view taken substantially as indicated along theline III--III of FIG. 1;

FIG. 4 is a horizontal sectional view taken substantially as indicatedalong the line IV--IV of FIG. 2;

FIG. 5 is a sectional view taken substantially as indicated along theline V--V of FIG. 4;

FIG. 6 is a fragmentary sectional view taken substantially as indicatedalong the line VI--VI of FIG. 5;

FIG. 7 is a sectional view taken substantially as indicated along theline VII--VII of FIG. 6;

FIG. 8 is a fragmentary sectional view taken substantially as indicatedalong the line VIII--VIII of FIG. 7;

FIG. 9 is a fragmentary sectional view taken substantially as indicatedalong the line IX--IX of FIG. 2;

FIG. 10 is a fragmentary sectional view taken substantially as indicatedalong the line X--X of FIG. 9; and

FIG. 11 is a diagrammatic view illustrating the operative relationshipbetween the pump structure of the present invention and functionallyrelated parts of a heavy vehicle power train and hydraulic system.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring to FIGS. 1-4 of the drawings, the improved pump structure ofthe present invention comprises a pump casing assembly, indicatedgenerally at 20, which includes a charging pump subassembly, indicatedgenerally at 21, and a scavenging pump subassembly, indicated generallyat 22. The pump casing elements forming the charging pump subassemblyinclude a drive end plate 23 and a first set of casing elementsconsisting of a torque converter charging pump element 24, atransmission charging pump casing element 25, and a charging subassemblytransition casing element 26. The scavenging pump subassembly 22consists of a second set of casing elements including a scavenging inletcasing element 27, a scavenging pump casing element 28, and a fluiddelivery end plate 29.

The casing elements 23-26 of the charging pump subassembly 21 arealigned by means of a pair of alignment pins 30 which make a snugsliding fit in alignment sleeves 31 and screw into threaded bores 32 inthe transition casing element 26. Assembly of the charging pumpsubassembly 21 is by means of four long machine screws 33 which havetheir heads seated in counterbores 34 in a transition face 35 of thetransition casing element 26, and the machine screws 33 extend throughaligned bores 36 in the casing elements 24, 25 and 26, and screw intothreaded bosses 37 which project from the outer surface of the drive endplate 23.

The three casing elements of the scavenging pump subassembly 22 arealigned with one another and with the charging pump subassembly 21 bymeans of guide pins 38 in the scavenging inlet casing element 27 and thefluid delivery end plate 29 which seat in sockets 39 in the scavengingpump casing element 28 and in the transition face 35 of the transitioncasing element 26. The three casing elements of the scavenging pumpsubassembly 22 are assembled by means of four long machine screws 40which have their heads recessed in counterbores 41 formed in a frontface 42 of the subassembly 22, and the machine screws 40 extend throughaligned bores 43 in the casing elements 27 and 28 and screw intothreaded bores 44 in the fluid delivery end plate 29.

As best seen in FIGS. 1 and 2, the fluid delivery end plate 29 isprovided with mounting flanges 45 in which there are bolt holes 46; andthere are also four peripheral mounting bosses 47 on the transitionalpump casing element 26, and aligned with the bosses 47 on the pumpcasing elements 27, 28 and 29 are mounting bosses 48, and continuousbolt holes 49 extend through the aligned bosses 47 and 48. The boltholes 46 and the bolt holes 49 receive mounting bolts 50 and 51,respectively, by means of which the subassemblies 21 and 22 areindependently secured to a housing wall H of a bevel gear housing whichis a part of the vehicle drive. The housing wall H has threaded holes H1into which the mounting bolts 50 are screwed to secure the scavengingpump subassembly 22 to the wall H and there are also threaded bolt holesH2 in the wall H which receive the mounting bolts 51 that secure thecharging pump subassembly 21 to the wall. In addition to securing thecharging pump subassembly 21 to the housing wall H, the threaded bolts51 also detachably secure the two subassemblies 21 and 22 in faceabutting relationship as illustrated in FIG. 1. In addition to themounting bolts 50, guide pins 52 which are aligned with the guide pins38 in the fluid delivery end plate 29 seat in holes H3 in the housingwall H.

Referring now to FIG. 4, the pump casing elements 23 and 24 cooperate todefine a torque converter charging pump cavity 53; and the casingelement 24 also cooperates with casing elements 25 and 26 to define atransmission charging pump cavity 54. The three casing elements of thesubassembly 22 cooperate to define scavenging pump cavities 55 and 55a.The pump casing elements of the charging pump subassembly 21 areprovided with a series of aligned pump drive shaft openings 56, 57 and58 which are provided with respective sleeve bearings 56a, 57a and 58a;and in the scavenging pump subassembly 22 are aligned pump drive shaftopenings 59, 60 and 61 which are provided, respectively, with sleevebearings 59a, 60a and 61a. A charging pump drive shaft segment 62 isjournalled in the sleeve bearings 56a-58a, while a scavenging pump driveshaft segment 63 is journalled in the bearings 59-61; and the two driveshaft segments have an axially interfitting drive connection provided bya slot 62a at the inner end of the drive shaft segment 62 and a lug 63aat an end of the drive shaft segment 63 which makes a sliding fit in theslot 62a. The drive shaft segment 62 has an end portion 62b whichextends through the drive shaft opening 56 in the drive end plate 23which is adapted for operative connection to driving means through adrive pulley assembly, indicated generally at 64, by means of which adrive pulley 65 is mounted upon the drive shaft segment 62 through asplined connection 62c. The drive pulley assembly forms no part of thenovel subject matter of the present invention, so it is not described indetail.

Alongside the drive shaft openings 56-58 in the charging pumpsubassembly 21 are idler shaft openings 66, 67 and 68 which are providedwith respective sleeve bearings 66a-68a; and alongside the drive shaftopenings 59, 60 and 61 in the subassembly 22 are idler shaft openings69, 70 and 71 which are provided, respectively, with sleeve bearings69a-71a. A charging pump idler shaft 72 is journalled in the sleevebearings 66a-68a, while an idler shaft 73 is journalled in the sleevebearings 69a-71a.

Keyed to the drive shaft segment 62 and to the idler shaft 72 in thetorque converter charging pump cavity 53 are meshing gear pump members74 and 75 which form a rotary, gear type torque converter charging pump;and on said shafts 62 and 72 in the transmission charging pump cavity 54are intermeshing gear pump members 76 and 77 which provide a rotarytransmission charging pump. Similarly, on the drive shaft segment 63 andthe idler shaft 73, in the scavenging pump cavity 55 are intermeshinggear pump members 78 and 79 which provide a first rotary scavengingpump; while intermeshing gear pump members 80 and 81 in the scavengingpump cavity 55a provide a second rotary scavenging pump. The firstrotary scavenging pump 78-79 scavenges fluid from a torque converter C,while the second rotary scavenging pump 80-81 scavenges fluid from atransmission T.

Referring now particularly to FIGS. 1, 2 and 5-10, the present hydraulicpump structure 20 is manifolded to provide a charging fluid inletpassage 82 (FIGS. 1, 5, 6 and 8); a torque converter charging deliverypassage 83 (FIGS. 3, 5, 6 and 7); a transmission charging fluid deliverypassage 84 (FIGS. 2, 7 and 8); a torque converter scavenging inletpassage 85 (FIGS. 1, 2, 9 and 10); a transmission scavenging fluid inletpassage 86 (FIGS. 2 and 9); and a scavenging fluid outlet passage 87(FIGS. 2 and 9).

Because of the fact that the pump structure is mounted on the gearhousing wall H with the fluid delivery end plate 29 abutting the wall,the wall is provided with holes which are seen in FIGS. 2 and 3 to be inregister with the ports for the passages 83, 84, 86 and 87, and saidholes are identified in FIG. 3 by the respective numerals H4, H5, H6 andH7.

When the structure 20 is assembled, annular seals 88, which are mountedin grooves in certain of the casing element faces in abutment with theadjacent casing element faces and with the wall H, seal the entirestructure against leakage from the pump cavities. In addition, leakagefrom the charging delivery passages 83 and 84 is minimized or providedby means of annular seals 89 (see FIGS. 6 and 8) at the abutting facesbetween the casing elements through which those passages pass.

INDUSTRIAL APPLICABILITY

The improved pump structure 20 of the present invention can be used inany hydraulic system having two rotary pumps that can be driven off thesame shaft. A particularly advantageous use is illustrated in FIG. 11,where the pump structure 20 is mounted on a housing wall H of a gearhousing G that is in direct communication with the housing for thehydraulic transmission T of a heavy vehicle. This permits a transmissioncharging conduit 90 to conduct fluid from the transmission chargingdelivery passage 84 to the transmission through the gear housing andalso permits a transmission scavenging conduit 91 to extend through thegear housing. This protects such conduits from damage that could resultfrom their being mounted in exposed locations, and also causes anyleakage from the conduits to remain inside the housing. Furthermore, theentrance to the charging fluid inlet passage 82 is very close to, anddirectly in line with the outlet from a screen F which is also mountedupon the wall H, so that a charging fluid conduit 92 may be straight andonly a few inches long. Likewise, although the torque converter chargingfluid conduit 93 must go outside the gear housing, its connection to thepump through the hole H4 is inside the housing, and thus more protectedthan would otherwise be the case. A portion of the gear housing Gprovides a sump S to receive scavenged fluid from the passage 87 throughthe conduit 94, for return to the pump through the screen F. Numeral 95designates a scavenging fluid conduit which connects the torqueconverter to the scavenging inlet passage 85 of the scavenging pumpsubassembly 22.

Other aspects, objects and advantages of this invention can be obtainedfrom a study of the drawings, the disclosure and the appended claims.The foregoing detailed description has been given for clearness ofunderstanding only and no unnecessary limitations should be understoodtherefrom as modifications will be obvious to those skilled in the art.

We claim:
 1. In a hydraulic system which has a plurality of pumps, animproved pump structure comprising:a pump casing assembly (20)consisting of a plurality of rotary pump casing elements (23-29)disposed in face abutting relationship, said casing elements (23-29)cooperating to define a first pump cavity (54) and a second pump cavity(55a), there being a plurality of manifold passages (82,84,86,87) formedin said casing elements (23-29) for admitting hydraulic fluid to saidcavities (54 and 55a) and delivering fluid from said cavities, and aseries of aligned pump drive shaft openings (56-61) connecting said pumpcavities, and said casing elements (23-29) including a fluid deliveryend plate (29) and a drive end plate(23); a drive shaft (62-63)journalled in said drive shaft openings (56-61) which has an end portion(62b) extending through an opening (56) in the drive end plate (23) andadapted (64) for operative connection to driving means; a first rotarypump (76-77) in said first pump cavity (54) and a second rotary pump(80-81) in said second pump cavity (55a), each of said pumps having apump member (76 or 80) mounted on the drive shaft (62-63), and saidmanifold passages including a first fluid inlet passage (82) foradmitting fluid to the first pump (76-77), a first fluid deliverypassage (84) from said first pump (76-77), said first fluid deliverypassage (84) having a port in said fluid delivery end plate (29), asecond fluid inlet passage (86) for admitting fluid to the second pump(80-81), and a fluid outlet passage (87) from said second pump (80-81),said fluid outlet passage (87) having a port to let fluid out of saidcasing assembly (20); sealing means (88-89) between said casing elements(23-29); and means (33,44,50,51) detachably securing said casingelements (23-29) in assembled, face abutting relationship.
 2. Theimproved structure of claim 1 in which the pumps (76-77 and 80-81) aregear pumps, a first gear (76 or 80) of each pump is on the drive shaft(62-63), the casing elements (23-29) are provided with aligned idlershaft openings (66-71), idler shaft means (72 and 73) is mounted in theidler shaft openings, and a second gear (77 or 81) of each pump is onthe idler shaft means (72-73).
 3. The improved structure of claim 1 inwhich the port of the fluid outlet passage (87) and an entrance to thesecond fluid inlet passage (86) are both in the fluid delivery end plate(29).
 4. The improved structure of claim 3 in which the casing elements(23-29) are pre-assembled into first (21) and second (22) subassemblies,said first subassembly (21) includes the drive end plate (23) and afirst set of casing elements (24-26) which define the first pump cavity(54) and which contain the first fluid inlet passage (82) and a firstpart of the first fluid delivery passage (84) terminating in an opendelivery end (84a), and said second subassembly (22) includes the fluiddelivery end plate (29) and a second set of casing elements (27 and 28)which contain a second part of the first fluid delivery passage (84)that has an open receiving end in communication with said open deliveryend (84a), said second set of casing elements (27 and 28) defining thesecond pump cavity (55a) and also containing the fluid outlet passage(87) which terminates at the port of said outlet passage (87) in thefluid delivery end plate (29), and a drive shaft segment (62 and 63) ineach subassembly (21 and 22), said segments (62 and 63) including anaxially interfitting drive connection (62a-63a).
 5. The improvedstructure of claim 4 in which first mounting means (50) secures thesecond subassembly (22) to a support (H), and second mounting means (51)secures the first subassembly (21) to the same support (H) and alsoprovides means detachably securing said two subassemblies (21 and 22) inabutting relationship with said drive connection (62a-63a) axiallyinterfitted.
 6. The improved structure of claim 3 which includes means(50 and 51) for mounting the casing assembly with the fluid delivery endplate (29) abutting a wall (H) of a housing (G) which communicatesdirectly with a hydraulic power element (T), said wall (H) having a hole(H5) registering with the port of the first fluid delivery passage (84),having a hole (H6) registering with the entrance to the second fluidinlet passage (86), and having a hole (H7) registering with the port ofthe fluid outlet passage (87), whereby all the fluid connections betweenthe pump structure (20) and the hydraulic power element (T) may belocated within said housing (G).
 7. The improved structure of claim 1 inwhich the casing elements (23-29) are pre-assembled into first (21) andsecond (22) subassemblies, said first subassembly (21) includes thedrive end plate (23) and a first set of casing elements (24-26) whichdefine the first pump cavity (54) and which contain the first fluidinlet passage (82) and a first part of the first fluid delivery passage(84) terminating in an open delivery end (84a), and said secondsubassembly (22) includes the fluid delivery end plate (29) and a secondset of casing elements (27 and 28) which contain a second part of thefirst fluid delivery passage (84) that has an open receiving end incommunication with said open delivery end (84a), said second set ofcasing elements (27 and 28) defining the second pump cavity (55a) andalso containing the fluid outlet passage (87), and a drive shaft segment(62 and 63) in each subassembly (21 and 22), said segments (62 and 63)including an axially interfitting drive connection (62a and 63a).
 8. Theimproved structure of claim 7 in which the casing elements (23-29) arepre-assembled into first (21) and second (22) subassemblies, said firstsubassembly (21) includes the drive end plate (23) and a first set ofcasing elements (24-26) which define the first pump cavity (54) andwhich contain the first fluid inlet passage (82) and a first part of thefirst fluid delivery passage (84) terminating in an open delivery end(84a), and said second subassembly (22) includes the fluid delivery endplate (29) and a second set of casing elements (27 and 28) which containa second part of the first fluid delivery passage (84) that has an openreceiving end in communication with said open delivery end (84a), saidsecond set of casing elements (27 and 28) defining the second pumpcavity (55a) and also containing the fluid outlet passage (87), and adrive shaft segment (62 and 63) in each subassembly (21 and 22), saidsegments (62 and 63) including an axially interfitting drive connection(62a and 63a).
 9. The improved structure of claim 1 in which there is anentrance to the second fluid inlet passage (86) in the fluid deliveryend plate (29) which includes means for mounting the casing assembly(20) with the fluid delivery end plate (29) abutting a wall (H) of ahousing (G) which communicates directly with a hydraulic power element(T), said wall (H) having a hole (H5) registering with the port of thefirst fluid delivery passage (84), and having a hole (H6) registeringwith the entrance to the second fluid inlet passage (86) whereby all thefluid connections between the pump structure (20) and the hydraulicpower element (T) may be located within said housing (G).
 10. In ahydraulic system for a heavy vehicle which has a hydraulic torqueconverter (C) and a hydraulic transmission (T), an improved pumpstructure comprising:a pump casing assembly (20) consisting of aplurality of rotary pump casing elements (23-29) disposed in faceabutting relationship, said casing elements (23-29) cooperating todefine a torque converter charging pump cavity (53), a transmissioncharging pump cavity (54), a first scavenging pump cavity (55), and asecond scavenging pump cavity (55a), there being a plurality of manifoldpassages (82-87) formed in said casing elements (23-29) for admittinghydraulic fluid to said cavities (53-55a) and delivering fluid from saidcavities, and a series of aligned pump drive shaft openings (56-61)connecting said pump cavities (53-55a), and said casing elements (23-29)including a fluid delivery end plate (29) and a drive end plate (23); adrive shaft (62-63) journalled in said drive shaft openings (56-61)which has an end portion (62a) extending through an opening (56) in thedrive end plate and adapted (64) for operative connection to drivingmeans; a rotary torque converter charging pump (74-75) and a rotarytransmission charging pump (76-77) in said respective charging pumpcavities (53 and 54), first and second rotary scavenging pumps (78-79and 80-81) in said scavenging pump cavities (55 and 55a) respectively,each of said pumps having a pump member (74,76,78 or 80) mounted on thedrive shaft (62-63), and said manifold passages (82-87) including acharging fluid inlet passage (82) for admitting fluid to the twocharging pumps (74-75 and 76-77), a torque converter charging fluiddelivery passage (83) from said torque converter charging pump (74-75),said torque converter charging fluid passage (83) having a port in saidfluid delivery end plate (29), a transmission charging fluid deliverypassage (84) from said transmission charging pump (76-77), saidtransmission charging fluid passage (84) having a port in said fluiddelivery end plate (29), a first scavenging fluid inlet passage (85) foradmitting fluid from the torque converter (C) to the first scavengingpump (78-79), a second scavenging fluid inlet passage (86) for admittingfluid from the transmission (T) to the second scavenging pump (80-81),and a scavenging fluid outlet passage (87) from said scavenging pumps,said passage (87) having a scavenging fluid outlet port; sealing means(88-89) between said casing elements; and means (33,44,50,51) detachablysecuring said casing elements (23-29) in assembled, face abuttingrelationship.
 11. The improved structure of claim 10 in which the portof the scavenging fluid outlet passage (87) and an entrance to thesecond scavenging fluid inlet passage (86) are both in the fluiddelivery end plate (29).
 12. The improved structure of claim 11 in whichthe casing elements (23-29) are pre-assembled into first (21) and second(22) subassemblies, said first subassembly (21) includes the drive endplate (23) and a first set of casing elements (24-26) which define thetwo charging pump cavities (53 and 54) and which contain the chargingfluid inlet passage (82) and a first part of each of the charging fluiddelivery passages (83 and 84) each of which terminates in a respectiveopen delivery end (83a or 84a), and said second subassembly (22)includes the fluid delivery end plate (29) and a second set of casingelements (27-28) which contain a second part of each charging fluiddelivery passage (83 and 84) each of which has an open receiving end incommunication with one of said open delivery ends (83a or 84a), thecasing elements of said second subassembly (22) defining the twoscavenging pump cavities (55 and 55a) and also containing the scavengingfluid outlet passage (87) which terminates at its outlet port in thefluid delivery end plate (29), and a drive shaft segment (62 or 63) ineach subassembly (21 or 22), said segments (62 and 63) including anaxially interfitting drive connection (62a-63a).
 13. The improvedstructure of claim 12 in which first mounting means (50) secures thesecond subassembly (22) to a support (H), and second mounting means (51)secures the first subassembly (21) to the same support (H) and alsoprovides means detachably securing said two subassemblies (21 and 22) inabutting relationship with said drive connection (62a-63a) axiallyinterfitted.
 14. The improved structure of claim 11 which includes means(50 and 51) for mounting the casing assembly (20) with the fluiddelivery end plate (29) abutting a wall (H) of a vehicle housing (G)which communicates directly with the hydraulic transmission (T), saidwall (H) having a transmission charging fluid hole (H5) registering withthe port of the transmission charging fluid passage (84), having atorque converter charging fluid hole (H4) registering with the port ofthe torque converter charging fluid passage (83), having a scavengingfluid hole (H6) registering with the entrance to the second scavengingfluid inlet passage 86, and having a scavenging fluid hole (H7)registering with the port of the scavenging fluid outlet passage (87),whereby all the fluid connections (90 and 91) between the pump structure(20) and the transmission (T) and a part of the charging connection (93)between the pump structure (20) and the torque converter (C) are locatedwithin said housing (G).
 15. The improved structure of claim 10 in whichthe casing elements (23-29) are pre-assembled into first (21) and second(22) subassemblies, said first subassembly (21) includes the drive endplate (23) and a first set of casing elements (24-26) which define thetwo charging pump cavities (53 and 54) and which contain the chargingfluid inlet passage (82) and a first part of each of the charging fluiddelivery passages (83 and 84) each of which terminates in a respectiveopen delivery end (83a or 84a), and said second subassembly (22)includes the fluid delivery end plate (29) and a second set of casingelements (27-28) which contain a second part of each charging fluiddelivery passage (83 and 84) each of which has an open receiving end incommunication with one of said open delivery ends (83a or 84a), thecasing elements of said second subassembly (22) defining the twoscavenging pump cavities (55 and 55a) and also containing the scavengingfluid outlet passage (87), and a drive shaft segment (62 or 63) in eachsubassembly (21 or 22), said segments (62 and 63) including an axiallyinterfitting drive connection (62a-63a).
 16. The improved structure ofclaim 10 in which the entrance to the second scavenging fluid inletpassage (86) is in the fluid delivery end plate (29) and which includesmeans (50 and 51) for mounting the casing assembly (20) with the fluiddelivery end plate (29) abutting a wall (H) of a vehicle housing (G)which communicates directly with the hydraulic transmission (T), saidwall having a transmission charging fluid hole (H5) registering with theport of the transmission charging fluid passage (84), having a torqueconverter charging fluid hole (H4) registering with the port of thetorque converter charging fluid passage (83), and having a scavengingfluid hole (H6) registering with the entrance to the scavenging fluidinlet passage (86), whereby all the fluid connections (90 and 91)between the pump structure (20) and the transmission (T) and a part ofthe charging connection (93) between the pump structure (20) and thetorque converter (C) are located within said housing.
 17. The improvedstructure of claim 10 which includes a direct, short connecting tube(92) between a fluid filter (F) and the entrance opening of the chargingfluid inlet passage (82).
 18. In a hydraulic system which has aplurality of pumps, an improved pump structure comprising:a first pumpsubassembly (21) comprising a plurality of pump casing elements (23-26),a first rotary pump (76-77) in a cavity (54) in said first pumpsubassembly (21), said first rotary pump (76-77) including a drive shaftsegment (62) which has an end portion (62b) extending through an endplate (23) of the subassembly (21) and adapted (64) for operativeconnection to driving means, and said drive shaft segment (62) having anexposed opposite end, a fluid inlet passage (82) for admitting fluid tothe first rotary pump (76-77), and a first part of a fluid deliverypassage (84) from said pump (76-77) in certain (25-26) of said casingelements which has an open end (84a) adjacent the exposed drive shaftend; a second pump subassembly (22) comprising a plurality of pumpcasing elements (27-29), a second rotary pump (80-81) in a cavity (55a)in said second pump subassembly (22), said second rotary pump (80-81)having a drive shaft segment (63) which has an end adapted to make anaxially interfitting drive connection (62a-63a) with the exposed end ofthe first drive shaft segment (62), a fluid inlet passage (86) foradmitting fluid to the second rotary pump (80-81), a fluid outletpassage (87) from said second rotary pump, and a second part of saidfluid delivery passage (84) which is adapted to communicate directlywith said open end (84a); first means (50) securing said second pumpsubassembly (22) to a support (H); second means (51) securing said firstpump subassembly (21) directly to said support (H) and in end abuttingrelationship to the second pump subassembly (22) with said axiallyinterfitting drive connection (62a-63a) engaged and with said two partsof the fluid outlet passage (84) in direct communication with oneanother; and sealing means (88 and 89) between the abutting ends of saidtwo pump subassemblies (21 and 22).
 19. The improved pump structure ofclaim 18 in which all the fluid passages (84,86 and 87) in the secondpump subassembly (22) are open at an end plate (29) of said second pumpsubassembly (22), and the support (H) is a wall of a housing (G) whichhas respective holes (H5, H6 and H7) registering with the open ends ofsaid passages (84,86 and 87), whereby all connections (90,91 and 94) tosaid passages (84,86 and 87) are within said housing (G).